Field of the Invention
The present invention relates to a fixing device that includes a flexible cylindrical rotary member and that fixes an image formed on a recording material to the recording material.
Description of the Related Art
In a fixing device that is mounted on an image forming apparatus using an electrophotography recording system and that uses a flexible rotary member, lateral shift of the rotary member in a generatrix direction during rotation of the rotary member is a problem. In order to restrict the lateral shift, a restricting member that restricts the lateral shift of the rotary member is sometimes provided at a position that opposes an end surface of the rotary member. Japanese Patent Laid-Open No. 2011-248285 discloses a fixing device including such a restricting member.
However, there is a demand for recent image forming apparatuses to provide high speed and save energy. This demand has caused an increase in the rotation speed of a rotary member and an increase in the pressure applied to an end surface of the rotary member when the rotary member contacts the lateral shift restricting member. In addition, in order to restrict the heat capacity of the rotary member, the thickness and diameter of the rotary member are being reduced. Therefore, the pressure per unit area applied to the end surface of the rotary member is increased. Further, there is a demand for recent image forming apparatuses to have a long life. This has increased the time that the end surface of the rotary member slidingly rubs the lateral shift restricting member. Accordingly, as the performance required of image forming apparatuses is improved, the end surface of the rotary member is becoming susceptible to scraping and the durability of the rotary member is becoming insufficient. Therefore, further improvement is demanded of a mechanism that restricts lateral shift of the rotary member.